Enter a full Vcs-* header, supported schemes are: Vcs-Bzr, Vcs-Cvs, Vcs-Darcs, Vcs-Git, Vcs-Hg, Vcs-Mtn, Vcs-Svn.
For Vcs-Git append -b branch to select the branch name; append [subdir] if the debian/ directory is not in the repository root.
The next upload will reset the information from the source package headers.